Viscose spinning process



United States Patent 3,116,354 VISCOSE SPINNING PRGCESS Paul V. Brewer, Elizahethton, Tenn., assignor, by mesne assignments, to Beaunit Corporation, New York, N .Y., a corporation of New York No Drawing. Filed May 2, 1957, Ser. No. 656,484 16 Claims. (Cl. 264190) This invention relates to an improved cellulose xanthate spinning solution and to an improved method for pro ducing high-tenacity regenerated cellulose products, especially yarn suitable for use in automobile tires, etc, from this improved spinning solution, and to the resulting products.

High-tenacity viscosity rayon is usually produced by spinning viscose in an acid-salt bath containing, in addition to sodium sulfate and sometimes magnesium sulfate, a zinc salt (see US. Patents No. 2,312,152 and No. 2,324,437), and stretching the freshl coagulated thread in a second hot water bath containing small amounts of acid and salt as described in US. Patent No. 2,192,074. As is well-known in the art, viscose composition, viscose ripeness, spin bath composition, and spin bath temperature must each be adjusted and correlated with one another to yield yarn having the most favorable physical properties, i.e., tensile strength, elongation, fatigue, heat stability, etc. In tire yarn, fatigue and heat stability are even more important than tensile strength. The elongation value of tire yarn should be less than that usually desired in textile yarn, and the loss in strength in plying and cabling should be low.

In response to consumer demand the viscose rayon producers have searched constantly for methods for further improving the physical properties of high tenacity yarn. Increasing the zinc sulfate content of the spin bath gives an improved yarn, but eventually a point is reached Where more zinc sulfate has but little further effect on the yarn properties. Another approach has been to add to the viscose, to the spin bath, or to both, various spinning modifiers.

Some investigators hold that the cellulose pulp (from cotton or wood) used in the production of high tenacity t viscose rayon should contain only small amounts of very low molecular Weight materials (dp. 75 or less) and that the cellulose chains in the pulp should have a uniform molecular weight, rather than a high average molecular weight with some very high molecular weight chains and some low molecular weight chains (see, for example, TAPPI, Volume 39, No. 1, pages 242-248, April, 1956, and Paper Trade Journal, September 3, 1956, pages 21- 25). A carefully prepared wood pulp, containing only a minimum amount of very low molecular Weight material, and having a uniform cellulose chain molecular weight distribution is said to be just as satisfactory for the pro duction of high tenacity viscose rayon as cotton pulp. The wood pulp sold by Rayonier, Inc. under the designation Cordenier J is an example of such a pulp. Others hold that when producing viscose for high tenacity yarn care should be taken that the cellulose chains in the high quality (high molecular weight) pulps, preferably cotton pulp, are broken down only as much as is necessary to obtain the optimum spinning viscosity, and that the amount of low molecular weight cellulose chains is not greatly increased. The importance of these latter factors in the production of high tenacity yarn has been brought out by specific disclosures in the patent art (see, for example, US. Patents No. 2,586,796, No. 2,592,355, and No. 2,732,279, and German Patent No. 838,936) Still others find it possible to produce high tenacity viscose rayon from Wood pulp of comparatively low average molecular Weight containing considerable very low molecular weight material. This is accomplished by reducing the alkali celluice lose ageing time and/ or temperature or by eliminating the ageing step completely, to avoid any considerable further degradation of the cellulose chains. Much of the very low molecular Weight material is removed from such pulps by the dip lye.

The yarn properties are also improved if green, '.e., substantially unripened, viscose is spun at a high salt point (see, for example, U.S. Patents No. 2,581,835 and No. 2,598,834).

Despite the improvements resulting from these and other efforts, the consumers of high-tenacity yarn have demanded still further improvement.

I have found, unexpectedly, that high-tenacity viscose rayon having improved physical properties, especially tensile strength and fatigue, may be obtained by spinning viscose containing a small amount of a soluble salt of a strong base and a Weak acid, in particular the soluble sulfides, but not excluding other such salts, such as sodium acetate, sodium phosphate, etc., in a zinc containing acid-salt spin bath in the presence of small amounts of a sugar, and preferably a hexose such as glucose or corn sugar, a polyalkylene glycol, or a derivative thereof, and one or more soluble hydroxy fatty acids, preferably a hydroxy lower fatty acid having from 2 to about 6 carbon atoms, such as hydroxyacetic acid, lactic acid, etc. The hydroxy group is preferably but not necessarily in alpha position. Of the soluble viscose coagulating salts of a strong base and a Weak acid, metal salts are preferred and of the latter alkali metal salts are especially useful. For commercial purposes, the sodium salts are highly advantageous. By soluble as applied to these salts, reference is intended to be made to their solubility in the environment of use irrespective of their solubility in water.

The soluble salt modifier is added only to the viscose. The glucose or corn sugar, the polyalkylene glycol or derivatives thereof and the hydroxy fatty acid modifiers may be added to the viscose, to the spin bath, or to both viscose and spin bath. Modifiers added to the viscose will gradually accumulate in the spin bath and there-fore the additions to such baths may be made taking that factor into account. The most favorable results are obtained if small amounts of the glucose or corn sugar, the poly alkylene glycol and the hydroxy fatty acid modifiers are dispersed and/or dissolved in both the salt-modified viscose and in the spin bath, though, if desired, the saltmodified viscose may contain only the glucose and the polyallcylene glycol modifiers, while the spin bath contains sufficient amounts of the glucose or corn sugar, polyalkylene glycol and hydroxy fatty acid with particular reference to assuring the presence in the spin bath of sufficient hydroxy fatty acid to greatly retard the degradation of the polyalkylene glycol component as Will be pointed out hereinafter.

While my modifiers are effective in the various conventional viscoses having different salt points or maturities, I have found that the greatest improvement is obtained by spinning viscose at a salt point of about 7.5 to about 9.0 or more (the salt point is the percent concentration of a sodium chloride solution which just coagulates a drop of the viscose; see e.g., Charles Doree, The Methods of Cellulose Chemistry, 1933, page 254), in an acid-salt bath containing about 4% to 8% or more, of a soluble zinc salt. High salt point (high maturity) viscose may be obtained, as those skilled in the art will recognize, by various expedients, as by increasing the amount of carbon bisulfide used in xanthation, by reducing the ripening or maturing temperature, or by using both expedients, or by adding sodium sulfite to the viscose, etc. My modifiers are effective when used with viscose made from the various types of the cotton pulps and wood pulps disclosed above.

I am aware that the viscose rayon spinning assistant art I 3 discloses the addition of polyalkylene oxides or glycols, or their ether or ester derivatives, to cellulose pulp or to alkali cellulose (see U.S. Patents No. 2,362,217, No. 2,392,103, No. 2,393,817, No. 2,423,469, No. 2,481,693, No. 2,623,875, No. 2,710,861, etc.), to viscose (U.S. Patents No. 2,359,750, No. 2,397,338, No. 2,442,331, No. 2,519,227, No. 2,572,217, and No. 2,664,360, and British Patents No. 541,099, and No. 557,218, etc.), and to spin bath (see U.S. Patents No. 2,359,749, No.2,442,331, No. 2,489,310, etc.). Also, I am aware that the prior art discloses the addition of water-soluble hydroxy fatty acids to viscose (see British Patent No. 309,147, German Patent No. 283,286, etc.) and to spin bath (see U.S. Patents No. 1,102,237, No. 1,376,672, and No. 1,393,199, and German Patent No. 283,286, etc.). I am also aware that the prior art discloses the addition of salts of strong bases and weak acids to viscose for various purposes (see, for example, U.S. Patents No. 896,715, No. 1,575,052, No. 1,773,923, No. 1,862,592, No. 2,064,356, No. 2,065,188, No. 2,086,309, No. 2,581,835, and No. 2,647,114, British Patents No. 242,242 and No. 272,939, and French Patents No. 728,682 and No. 899,905, etc.). I am further aware that the prior art discloses the use of glucose in viscose spinning (see, for example, U.S. Patents No. 970,589, No. 1,393,199, No. 1,864,244, No. 1,955,239 and No. 2,397,338, and British Patents No. 15,752 (1910) and No. 332,628, etc.), but I am not aware of any disclosure of the combined use of these modifiers in viscose spinning for the purpose of improving the physical properties, in particular the fatigue value and the cord strength of tire yarn, of the regenerated cellulose product. The greatly improved physical properties are obtained only if the yarn is spun in the presence of sufiicient amounts of all four modifiers. When the soluble viscose-coagulating salt selected as additive is one normally formed as a byproduct of viscose production and maturation, the amount of the additive is in excess of that produced as a byproduct.

It is not clear how these four modifiers coact to improve the yarn properties. The improved results are, in part, due to the fact that the hydroxy fatty acid acts as a preservative for the glycol polymer in the hot acid coagulating bath. The glucose or corn sugar has a very favorable etfect on tire yarn cord strength and on fatigue values, perhaps, among other things, because it softens or plasticizes the yarn. The soluble strong base-weak acid salt and the sodium salts formed when the hydroxy fatty acids are added to the viscose exert a coagulating effect on the viscose and a buffering action against the strong acid of the spin bath. Both efi'ects favor the improvement of the yarn properties.

My polyakylene glycol-type modifiers are effective only if their molecular weight is about 400 or more. These compounds are so sensitive to acid and to elevated spin bath temperature that in the absence of a hydroxy fatty acid in accordance with the present invention a polyalkylene glycol having an average molecular weight of about 3300 is quickly degraded by the hot acid of a conventional spin bath to an average molecular weight of as low as about 350. It will be understood that a polyalkylene glycol becomes less effective, and finally completely ineffective as a spinning modifier, as its molecular weight drops. The addition of a small amount of a soluble hydroxy fatty acid in otherwise conventional viscose spinning retards this degradation so that the average molecular weight of a polyalkylene glycol falls, for example, no more than from about 3300 to about 900 to 1100. If a sufiicient amount of hydroxy fatty acid is not present in the spin bath, in an extended run the physical properties of the yarn decline steadily from the high values for yarn spun in fresh spin bath containing undegraded polyalkylene glycol modifier. It appears that in order to derive the fullest possible benefit from the synergistic effect of the hydroxy fatty acid it is necessary to have present in a spin bath, either by direct addition or by carry-over from the viscose or both, a certain minimum amount thereof, as will be described more fully hereinafter.

Carbowax 4000, a Carbide and Carbon Chemical Co. polyalkylene glycol having an average molecular weight of about 3300 is a preferred modifier. Lower molecular weight products can be use if the average molecular weight of the modifier in the spin bath does not fall below about 400, preferably not below about 1000, and products having an average molecular weight of up to about 7,500 are effective. The very high molecular weight products (for example, Carbowax 20,000), which should not be degraded to the potentially dangerous point of about 400 average molecular weight as rapidly as Carbowax 4000, are not efficient modifiers, in part, at least, because these higher molecular weight compounds are removed from the spin bath by the yarn and the spin bath filter. The enhancing action of my hydroxy fatty acid modifier makes possible the efiicient use of a medium molecular weight alkylene glycol polymer modifier in spin bath.

My modifiers are most efiective when the strong baseweak acid salt, the glucose or corn sugar and the poly alkylene glycol are dissolved and/or dispersed in the viscose and when the polyalkylene glycol, the hydroxy fatty acid and the glucose or corn sugar are dissolved and/or dispersed in the spin bath. If desired, the hydroxy fatty acid may be added to the viscose and the glucose addition to the spin bath may be omitted.

It is, therefore, an object of the present invention to provide an improved method for producing regenerated cellulose products, such as yarn, ribbon, film, etc., from viscose.

Another object is to provide an improved method for spinning high tenacity viscose rayon.

A further object is to provide an improved zinc acidsalt type coagulating bath for the production of high tenacity yarn from viscose.

Still another object is to provide an improved method for spinning high salt point viscose.

Yet another object is to provide an improved method for spinning green viscose.

Still other objects are to provide novel and improved viscose compositions as well as improved regenerated cellulose products having commercially more desirable physical properties, especially in regard to fatigue and strength characteristics.

Other objects of the invention will appear hereinafter.

The following examples illustrate various methods of applying the principles of the invention.

EXAMPLES 1-2 Conventional viscose spinning solutions containing about 6.3% cellulose and about 6.0% alkali, calculated as NaOI-I, were prepared by the well-known methods from a wood pulp sold by Industrial Cellulose Co., Ltd., under the designation SK Tenacell, using about 35 /2% CS based on cellulose in alkali cellulose. When the xanthate crumbs were dissolved in lye to form viscose, varying amounts of Carbowax 4000 (a Carbide and Carbon Chemical Co. polyethylene glycol having an average molecular weight of about 3300) and sodium sulfide flakes (about 63% Na s) were added. Glucose was also added to one of the viscose spinning solutions. The present modifier additions given in Table 1 are all based on cellulose in alkali cellulose.

These viscose spinning solutions were converted into 1650 denier 720 filament tire yarn by extruding at salt point about 8.0 and ball fall viscosity about 45 into a conventional continuous spinning process using a 65 C. spin bath containing about 106 g./1. H 230 g./l. Na SO g./l. ZnSO 0.050 g./l. Carbowax 4000 and 0.20 g./l. hydroxyacetic acid and a separate hot acid regenerating bath. The spin bath into which the glucosemodified viscose was extruded contained 1.75 g./l. glucose. The spin bath for the other viscose contained no glucose. The freshly extruded threads were subjected to a net stretch of about 92% and were washed, after treated and dried as is usual in the production of such yarn.

The conventional strength, elongation and fatigue tests were made on a 12.0/ 12.0 cable construction. (A 12.0/ 12.0 cable construction has 12.0 turns per inch 2 ply twist, and 12.0 turns per inch S cable twist). The data for the yarns are given in Table 1. The expressions conditioned strengt and conditioned breaking elongation refer to yarn having 12% moisture regain. The ovendry cable strength value is determined on a cable dried overnight in an oven at 90 C. and tested while the moisture regain is still less than 1%.

The glucose has increased the fatigue rating by about 22%.

EXAMPLES 3-4 Conventional viscose spinning solutions containing about 7.0 cellulose and about 6.5% alkali, calculated as NaOH, were prepared from SK Tenacell as in Examples 1-2, using about 37 /2% CS based on cellulose in alkali cellulose. When the cellulose xanthate was dissolved in lye to form viscose, varying amounts of Carbowax 4000, sodium sulfide flakes (about 63% Na s) and hydroxyacetic acid were added. Glucose was also added to one of the viscose spinning solutions. The percent viscose modifier additions given .in Table 2 are all based on cellulose in alkali cellulose.

These spinning solutions were converted into 1650 denier 720 filament tire yarn by extruding them at salt point about 8.0 and ball fall spinning viscosity about 45 in a conventional continuous spinning process using a 65 C. spin bath containing about 108 g./l. H 80 220 g./l. Na SO 95 g./l. ZnSO and Carbowax 4000, hydroxyacetic acid and glucose modifiers as indicated in Table 2, using a separate hot acid regeneration bath. The freshly extruded threads were subjected to an initial stretch of about 87.8% and a net stretch of about 81.1%. The yarn was washed, aftertreated and dried as is usual in the production of such yarn.

The conventional strength, elongation and fatigue tests were made on the singles yarn and on a 12.0/ 12.0 cable construction. The data for the yarns are given in Table 2. This spinning was carried out during several days on regular production machines and the figures given are averages tor the runs.

Table 2 VISCOSE Example N o 3 4 Carbowax 4000, percent-.- 0. 275 0.275 Hydroxyacetie acid, percent. 0. 30 0.30 Sodium sulfide flakes (63% N 3.0 3.0 Glucose, percent 0. 30

SPIN BATH Carbowax 4000, g./l 0.05 0.05 Hydroxyacetic acid, g./l 0.20 0. 2O Glucose, g'./l 1. 75

SINGLES Conditioned strength, g./d 4. 34 4. 34 Wet strength, g./d 2. 94 2. 91 Wet/ dry ratio 0. 677 0. 669 Conditioned elongation, percent 10.7 10. 4 Wet elongation, percent 20. 2 19. 9 Heat stability 98. 2 98. 8

120/120 CABLES Conditioned Strength, g./d 3.10 3.13 Oven-dry strength, g./d 3. 71 3. 86 Conditioned strength, lbs 25. 99 26. 35 Oven-dry strength, lbs 31. 36 32. 43 Strength lost in cabling, percent 28. 3; 28. 3 Fatigue 134 105 The glucose has increased the fatigue rating by about 24%.

EXAMPLES 5-6 A conventional viscose spinning solution containing about 6.3% cellulose and about 6.0% alkali, calculated as NaOH, was prepared by the well-known methods from a wood pulp sold by industrial Cellulose Co., Ltd, under the designation Tenacell SK, using 39.0% CS based on cellulose in alkali cellulose. When the cellulose xanthate crumbs were dissolved in lye to form the viscose, about 0.275% Carbowax 4000, about 0.30% hydroxyacetic acid, about 0.30% glucose and about 4.0% sodium sulfide flakes (about 63% Na s), each based on cellulose in alkali cellulose, were added to the viscose.

This viscose spinning solution was converted into 1650 denier 720 filament tire yarn in a conventional continuous process by extruding it through spinnerettes having 60 mu holes into 70 C. spin baths containing about 106 g./l. H 50 100 g./l. ZnSO 0.050 g./l. Carbowax 4000, 0.150 g./l. hydroxyacetic acid, and glucose as indicated in the table, using a separate hot acid regenerating bath. The freshly extruded threads were subjected to a net stretch of about 92%, and were washed, aftertreated and dried as usual in the production of such yarn.

The conventional strength, elongation and fatigue tests were made on the singles yarn and on a 12/12 cable construction. The data for the yarns are given in Table 3.

Table 3 SPIN BATH Example N0 5 6 Carbowax 4000, g./l 0. 050 0. 050 Hydroxyaeetic acid, g. 0. 150 0.150 Sodium sulfide flakes (about (53% Na s), percent 4.0 4. 0 Glucose, g./l 1.

SINGLES YARN Conditioned strength, g./d 4. 25 4. 2S W'ct Strength, g./d 3. 1.7 2.90 Conditioned elongation, percent. 9. 0 10.0 Heat Stability 99. 5 95. 6 Wet/dry ratio 0. 7 l1 0. 678

12/12 CABLES Conditioned strength, g./d 3. 29 2. Oven-dry strength, g./d 3. S6 3. 41 Conditioned elongation, perceri 12.5 10.8 Strength lost in cabling, percent. 23. 5 32.6 Fatigue 181 98 1 No glucose was added directly to the spin bath but, due to carryover of glucose from the viscose, about 1 g./l. glucose was present in the spin bath.

The glucose addition to both viscose and spin bath has increased the cord strength and the fatigue value and has reduced the loss of strength in cabling.

The physical properties of high tenacity yarn, in particular the tensile strength and fatigue, are improved by increasing the alkali content of the viscose, as from about 6.0% NaOH to 6.5% NaOH, or more, in the approximately 7.0% cellulose viscose disclosed in the examples. However, these high alkali viscoses do not spin well unless modifiers are used. The use of the modifiers thus makes it possible to obtain the further advantages resulting from the use of high alkali viscose.

I have found that to obtain the best yarn properties there should preferably be present in the viscose about 0.ll.0%, and preferably about 0.-0.40% glucose, from about 0.ll.0% of the polyalkylene glycol component, based on cellulose in alkali cellulose. Especially good results are obtained when the polyalkylene glycol component is present in the viscose to the extent of about O.20.35%. With regard to the hydroxy fatty acid component I have found that from about 0.l1.-0%, based on cellulose in alkali cellulose, may be usefully employed in the viscose, especially good results being obtained when about 0.20-0.40% of the hydroxy fatty acid component is present in the viscose, although as pointed out above all of this component may if desired be added directly to the spin bath. In addition to the polyalkylene glycol the viscose should contain from about 25% of the soluble viscose coagulating salt such as technical grade sodium sulfide in the form of sodium sulfide flakes (about 63% Na s) preferably about 34% sodium sulfide flakes, based on cellulose in alkali cellulose.

From about 0.0020.050% or more of polyalkylene glycol based on the weight of the spin bath should be present in the spin bath, irrespectively of whether by direct addition or by carry-over from the viscose, or both. Particularly desirable results are obtained where this range is about 0.003-'O'.0l0%. The hydroxy fatty acid additive is preferably present to the extent of about 0.01250.050% or more, preferably about 0.01250.020% based on the weight of the spin bath. The spin bath should also contain about 01-03% glucose, preferably about 01-02% glucose, based on the weight of the spin bath.

While a polyethylene glycol having an average molecular weight of about 3,300, such as Carbide and Carbon Chemical Companys Carbowax 4000, is preferred for the practice of this invention lower molecular weight products may be employed if the average molecular weight of the modifier in the spin bath does not fall below about 400, preferably not below about 1000, and products having an average molecular weight of up to about 7,500 are useful. IEther and ester derivatives of fatty acids having a polyalkylene oxide chain containing at least about 25 ethylene oxide and/or propylene oxide groups are suitable modifiers. The various polyoxyethylene compounds disclosed in U .5. Patents No. 2,359,749, No. 2,359,750 and- No. 2,519,227 are useful modifiers. When the terms polyalkyle-ne glycol or oxide are used in the specification and claims it is intended to include also their ether and ester derivatives, including the hydroxy fatty acid esters, as Well as the mixed polyethylene polypropylene oxide derivatives.

My modifiers may be incorporated, separately or together, in the viscose spinning solution at any time prior to spinning. They may be incorporated in the pulp, or in the alkali cellulose, or added to the viscose at any time prior to spinning. A uniform dispersion of the modifiers in the spinning solution is most readily obtained if the modifiers are added to the mixer when the cellulose xanthate is dissolved in lye from the viscose.

The process may obviously be modified without departing from the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

1. A process for the production of improved cellulosic products which comprises modifying a viscose by adding thereto a soluble viscose-coagulating salt of a strong base and a weak acid, and extruding the resultant viscose into an acid spin bath in the presence of a sugar, a polyalkyl- 8 ene glycol having an average molecular weight of at least about 400, and an hydroxy fatty acid.

2. A process for the production of improved cellulosic products which comprises modifying a high maturity viscose by adding thereto a soluble viscose-coagulating salt of a strong base and a weak acid, and extruding the resultant viscose into an acid spin bath in the presence of a sugar, a polyalkylene glycol having an average molecular weight of at least about 400, and an hydroxy fatty acid.

3. A process as defined in claim 2 in which the polyal kylene glycol is selected from the group consisting of polyethylene glycol, polypropylene glycol and mixed polyethylene-polypropylene glycols having an average molecular weight of from about 400 to about 9,000.

4. A process as defined in claim 3 in which the sugar, the soluble viscose-coagulating salt, the polyalkylene glycol, and the hydroxy fatty acid are present in the viscose in an amount from about 0.101.0%, 2-5.5 0.1l.0%, and 0.11.0%, respectively, based on cellulose in alkali cellulose and the sugar, the polyalkylene glycol, and the hydroxy fatty acid are present in the spin bath in an amount from about 01-03%, 0.0020.050%, and 0.0l250.050%, respectively, based on the weight of the spin bath.

5. A process as defined in claim 3 in which the sugar, the soluble viscose-coagulating salt, the polyalkylene glycol, and the hydroxy fatty acid are present in the viscose in an amount from about 0.l00.40%, 3.04%, 0.2-0.35%, and 0.200.40%, respectively, based on cellulose in alkali cellulose, and the sugar, the polyalkylene glycol, and the hydroxy fatty acid are present in the spin bath in an amount from about 01-02%, 0.0030.0l0%, and 0.0l250.020%, respectively, based on the Weight of the spin bath.

6. A process as defined in claim 3 in which the hydroxy fatty acid contains from 2 to about 6 carbon atoms per molecule.

7. A process as defined in claim 3 in which the viscose has a salt point of about 7.5 to about 9.0.

8. In a process for the production of improved cellulosic products by extruding viscose to which sodium sulfide has been added into an acid spin bath, the improvement which comprises carrying 'out the extrusion in the presence of further additives comprising a polyalkylene glycol having an average molecular weight of at least about 400, a hydroxy fatty acid, and a sugar.

9. A process as defined in claim 8 in which the sugar is glucose.

10. A process as defined in claim 9 in which at least one of said further additives is incorporated in the viscose prior to extrusion.

11. -A process as defined in claim 9 in which at least one of said further additives is incorporated in the spin bath.

12. A viscose solution containing a soluble viscosecoagulating salt of a strong base and a weak acid, a polyalkylene glycol having an average molecular weight of from about 400 to about 9,000, a hydroxy fatty acid and a sugar.

13. A high maturity visc'ose solution to which has been added a soluble viscose-coagulating metal salt, a pclyalkylene glycol having an average molecular weight of from about 400 to about 9,000, a hydroxy fatty acid, and a sugar.

14. A high maturity viscose solution having a salt pointof about 7.5 to about 9.0 and containing as additives at least 2% sodium sulfide, from about 01-10% of polyalkylene glycol having an average molecular weight of from about 1000 to about 7500, and from about 0.1-1.0% of a hydroxy fatty acid, and from about 0.11.0% of glucose, based on cellulose in alkali cellulose.

15. An acid spin bath for regenerating cellulose in the production of extruded products from viscose, comprising a mineral acid, a soluble zinc salt, and additives for improving the regeneration of cellulose from the viscose References Cited in the file of this patent UNITED STATES PATENTS 970,589 Wilson Sept. 20, 1910 1,102,237 Bronnert July 7, 1914 1,955,239 Kampf et a1. Apr. 17, 1934 2,011,227 Maxwell -1 Aug. 13, 1935 2,064,118 Huttinger et al Dec. 15, 1936 10 Soukup July 13, 1943 'MacLaurin Apr. 22, 1952 Richter Aug. 11, 1953 Dietrich Dec. 7, 1954 Drisch Mar. 29, 1955 Tachikawa J an. 24, 1956 Hill July 28, 1959 FOREIGN PATENTS Great Britain Dec. 14, 1955 Great Britain Dec. 12, 1956 OTHER REFERENCES Ott, E.: Cellulose and Cellulose Derivatives, Inter- 15 science P-wb., NY. (1946), page 845.

tific Library.)

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1. A PROCESS FOR THE PRODUCTION OF IMPROVED CELLULOSIC PRODUCTS WHICH COMPRISES MODIFYING A VISCOSE BY ADDING THERETO A SOLUBLE VISCOSE-COAGULATING SALT OF A STRONG BASE AND A WEAK ACID, AND EXTRUDING THE RESULTANT VISCOSE INTO AN ACID SPIN BATH IN THE PRESENCE OF A SUGAR, A POLYALKYLENE GLYCOL HAVING AN AVERAGE MOLECULAR WEIGHT OF AT LEAST ABOUT 400, AND AN HYDROXY FATTY ACID. 